Crop Genebank Knowledge Base

• Acquisition agreements and permits

The samples should have been acquired from collectors, genebanks or other sources with appropriate material acquisition or transfer agreements and permits in line with national and international regulations regarding conservation, distribution and use.

• Passport information

Samples should be accompanied by adequate passport information especially cultivar name, collector number and pedigree (for genetic stocks and improved material) to ensure that each sample does not already exist in the genebank. The minimum required passport data may include the following:

Samples should be accompanied by adequate passport information especially cultivar name, collector number and pedigree (for genetic stocks and improved material) to ensure that each sample does not already exist in the genebank. The minimum required passport data may include the following:

A. Samples from collecting missions
- Common crop name and/or genus and species
- Collecting number
- Location of collecting site
- Country of origin
- Collecting date
- Phenology
- Collecting source
- Number of plants sampled

B. Samples received as donations:
- Common crop name and/or genus and species
- Accession name and/or other identification associated with the sample
- Pedigree information and breeding institute’s details (for breeding lines)
- Phenology
- Acquisition source
- Country of origin
- Donor accession number (if applicable)

• Distinctiveness

New samples should be genetically distinct from any other accessions already registered in the genebank. Two samples may have identical or very similar names and identical grain characteristics but may be genetically distinct, while samples with very different names may be genetically similar.

Morphological, biochemical and molecular approaches can be used to identify duplicates, depending on the facilities and resources available in the genebank. The following tests can be performed:

A. Morphological
- The suspected duplicates are grown side by side in the field or in a greenhouse and differences between morphological characteristics such as plant height, flowering time, leaf and flower size, and shape and colour are compared.
- The candidate accession is defined as distinct when it is found to differ significantly in at least one characteristic from existing registered accessions.
- Morphology-based distinctness tests can be similar to the crop-specific set of characteristics that comply with guidelines set by the International Union for the Protection of New Varieties of Plants (UPOV, 1991). If necessary, these characteristics can be assessed over two or three seasons. This may not be practical in landraces with high within-accession variation, however.
- The statistical procedure to assess distinctness is the t-test.

B. Biochemical
When phenotypic comparison does not provide enough evidence of distinctness, biochemical methods such as electrophoresis of seed (or other plant parts) proteins and isozymes can be used for improving the comparison of morphological traits and to discriminate the samples.

C. Molecular
DNA markers such as AFLPs, SSRs and SNPs offer powerful discriminating tools and can be successfully applied in checking genetic relatedness between samples, provided that this approach is feasible and cost effective. For more details on molecular methods, see de Vicente and Fulton (2003).
If the samples being compared are confirmed to be duplicates, genebanks are recommended to bulk the seeds or plant materials and treat them as one entity. If the sample is identical to an existing accession, maintain it under the original accession number.

• Plant health

Each sample should be accompanied by a phytosanitary certificate and additional declarations as required under the host country’s phytosanitary regulations.

Seed or plant samples should be inspected by visual examination under a stereoscopic microscope. They should be free of pathogens, fungal growth, bacterial and viral infections, and insects.

• Sample quality and quantity

Seeds or plant materials should be of the highest quality and in adequate numbers for storage.

--> In general, the percentage germinated should not be below 85% for cultivated species or below 75% for the wild species.

Seed or plant materials quantity should be sufficient to conduct at least three regenerations. This will ensure that seeds or plant materials are still available for another planting even if the first attempt to regenerate fails.

• What if minimum conditions are not met?

If the sample does not meet the required conditions, assign a temporary number until the sample is ready to receive a permanent registration number. The temporary number should be easily distinguishable from other accession numbers.

a) Agreements and permits
Contact the collector or donor for the necessary agreements defining the status of samples with regard to conservation and further use.

b) Duplicate accessions
Confirm duplication and assign the sample as a new seed or plant lot under the original accession number.
c) Missing passport information
Write to the collector or donor of germplasm to request missing information.

d) Poor seed health
If seeds contain pathogens or insects, send the sample to a phytopathologist or entomologist for treatment. If it is possible to acquire a replacement sample, immediately incinerate the sample and make note of the action taken and the justification; request a fresh sample from the donor.
e) Inadequate seed quality and quantity
Regenerate the sample immediately.

• Restructuring samples

In self-pollinating crops, if a sample comprises of a physical mixture of two or more distinct lines or species, they may be subdivided and maintained as distinct accessions. In this case, subdividing the sample into its components helps in effective maintenance of genetic integrity. Note that subdivision should not be undertaken if variation in the original sample is continuous, as in highly cross-pollinating crops.

A genebank numbering system should be simple and practical to use.

1. Consecutive alpha numeric or numeric codes must be used for each new accession acquired. Assigned numbers are usually preceded by an acronym (such as GBK for Genebank of Kenya) to identify each sample with its registered genebank. Additional information such as year of acquisition and crop code should not be incorporated into an accession number. This code must be linked to all subsequent information about this sample: passport data, designation status and taxonomic information.

2. If large collections of germplasm are maintained, separate but sequential accession numbering may be given for each crop. This approach is not recommended if the genebank is small or has many crops, however.

3. Avoid assigning ‘reserved’ numbers for particular crops (for instance, 1 to 500 for maize, 501 to 1000 for cowpea) or for wild species when using a single numbering system

Documentation

Documenting the information received along with a sample is an important aspect of registration. Information documented at registration consists of passport data providing basic information for identification and general management of individual accessions.
Much of this information is either recorded when the sample is collected or accompanies the sample if it is received from other sources. The use of internationally accepted descriptor lists to document passport information simplifies data exchange between genebanks. The standard Multi-crop Passport Descriptor (MCPD) list developed by FAO and IPGRI is available at www.bioversityinternational.org/publications/pdf/124.pdf.

Information systems

An information management system must be created in each genebank. This database must be searchable by the genabank curators and staff for specific information through a range of queries. The information system must keep a record of genebank operation data, including storage location, stocks, monitoring, health tests and the distribution status. The same system must also manage germplasm orders, shipment related information and files genebanks ‘contacts’ information.
Bar-coding is a useful tool that can compliment a genebank information system.

Further reading

Engels J.M. and Visser, L. (eds.). 2003. A guide to effective management of germplasm collections. IPGRI Handbook for Genebanks No.6. IPGRI, Rome, Italy.

de Vicente, C. and Fulton, T. 2003. Using molecular marker technology in studies on plant genetic diversity: Learning module Vol 1. IPGRI, Rome, Italy.

International Union for the Protection of New Plant Varieties (UPOV). 1991. International Convention for the Protection of New Varieties of Plants. UPOV, Geneva. (http://www.upov.int)